The IEEE standard 1394b “High Performance Serial Bus” relates to serial high-speed data transfer between peripheral devices and a computer or between peripheral devices and computers. It standardizes not only a copper transmission line but also optical transmission lines comprising a plastic fiber or a glass fiber. The standard defines two different electrical contacts, a bilingual contact and a beta plug contact. The beta plug contact has nine pins and is in the form of a media-independent contact, that is to say that it is possible to connect any desired transmission media to the contact. A bilingual contact can be used only for copper media and is of no importance in the present context.
The IEEE 1394b standard is used, in particular, for high-speed data transfer between multimedia appliances and laptops. Since such appliances frequently have only small physical dimensions, there is normally a problem in implementing the transceiver required for electro-optical conversion on the interface card in a respective appliance in order to be able to connect optical transmission links. If the available space is not sufficient to integrate a transceiver, it is necessary to use an externally arranged interface card which has a copper input to the terminal and optical outputs to the optical transmission links. In this case, such an external interface card needs to have a physical layer chip implemented on it which provides functions on the physical layer of the data transfer. Such external interface cards are disadvantageously associated with high costs.
Physical layer chips control data transfer on the physical layer of the OSI reference model. The tasks of a physical layer chip include setting up and maintaining physical connections between adjacent stations. The voltage levels used are also defined, for example.
Such a physical layer chip is manufactured, by way of example, by the company Texas Instruments under the name TSB41BA3, “IEEE 1394b Three-Port Cable Transceiver/Arbiter”. The appropriate specification can be retrieved on the Internet at http://focus.ti.com/lit/ds/symlink/tsb41ba3.pdf. The content of this specification is incorporated in the present application by reference.
There is a need for media-independent interfaces, particularly based on the IEEE 1394b standard, and also for associated plug-in opto-electronic transceivers with likewise standardized ports which, on the basis of an existing standard, extend the functionalities provided by the standard and consequently permit broad use, associated with few restrictions, of plug-in opto-electronic transceivers and optical transmission media.